2,825 research outputs found

    Parametric amplification and stochastic resonance in bio-inspired hair flow sensors

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    Inspired by crickets and its perception for flow phenomena, artificial hair flow sensors have been developed successfully in our group. The realization of array structures and improvement of fabrication methodologies have led to better performance, making it possible to detect and measure flow velocities in the range of sub-mm/s. To improve the performance of these artificial hair flow sensors even further, we will make use of non-linear effects. In nature a wide range of such effects exist (filtering, parametric amplification, etc.) and can give a rise\ud in sensitivity, dynamic range and selectivity. Here, we propose to use parametric amplification and stochastic resonance to improve our flow sensor performance

    Simulation studies of parametric amplification in bio-inspired flow sensors

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    In this paper the effect of parametric amplification in MEMS-based air-flow hairsensors is studied. With an AC-voltage controlled torsional stiffness the rotation of the hair can be influenced. With the appropriate amplitude, phase and frequency, the rotation of the torsional hair system is increased with respect to the case without parametric amplification. Therefore, parametric amplification is identified as a method to improve the performance of MEMS-based hair air flow sensors

    Map estimation of air-flow dipole source positions using array signal processing

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    In nature, fish have the ability to form flow-based maps to assist localizing predator or prey using the lateral-line system. Yet it is not fully understood what techniques are used by fish to draw these flow maps. Biologists try to figure out fish techniques by investigating different hypotheses [1]. Inspired by the lateral line of fish, we propose in this paper model based array signal processing techniques used to visualize the air-flow maps. The results show an ability to visualize the flow field generated by a dipole source using lateral-line system

    On the accuracy of the finite difference method for applications in beam propagating techniques

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    In this paper it is shown that the inaccuracy in the beam propagation method based on the finite difference scheme, introduced by the use of the slowly varying envelope approximation, can be overcome in an effective way. By the introduction of a perturbation expansion the accuracy can be improved as much as wanted, often nearly without any increase of the computation time. An error analysis is given and the method is illustrated by an example

    New formulation of the beam propagation method based on the slowly varying envelope approximation

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    We combine the theoretical results of some recent publications on the beam propagation method based on the finite difference method (FDBPM) and the slowly varying envelope approximation (SVEA). The use of the SVEA leads to a considerable reduction of the computation time but introduces a fundamental error in the phase velocity of a given mode and also to an error due to the finite step size along the propagation direction. A new, effective scheme is given, which results in a considerable reduction of these errors, without much increase of the computational effort. An error analysis and a few results of applications are given

    Efficient interface conditions for the finite difference beam propagation method

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    It is shown that by adapting the refractive indexes in the vicinity of interfaces, the 2-D beam propagation method based on the finite-difference (FDBPM) scheme can be made much more effective. This holds especially for TM modes propagating in structures with high-index contrasts, such as surface polaritons. A short discussion is given on the applicability of the FDBP

    Long-range elastic guidance mechanisms for electrostatic comb-drive actuators

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    The range of motion and output force of the often used electrostatic comb-drive with folded flexure straight guidance, as shown in Figure 1, is limited by sideways instability due to poor sideways stiffness of the folded flexure at relatively large deflections [1]
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